Damping devices of this type are, for example, part of dry or wet friction clutch installations, or also of clutch installations intended to lock up a hydrodynamic converter.
A combustion engine exhibits irregularities due to the succession of combustion events in the engine cylinders. Torsion damping means allow these irregularities to be filtered before engine torque is transmitted to a transmission. This is because the vibrations must be damped before they enter the transmission and produce unacceptably troublesome noise.
To accomplish this, it is known to interpose a torsion damping device between the engine shaft and the transmission shaft. The torsion damping device is generally arranged in a clutch system that allows temporary rotational connection of the engine shaft to the transmission shaft.
The torsion damping device generally has first damping means that act by interposition of circumferentially acting elastic members between a torque input element and a torque output element.
Such first damping means are advantageously supplemented by second damping means using pendulum flyweights. These pendulum flyweights, also called “pendulum oscillators,” extend around the rotation axis of the drive shaft and are free to oscillate around a notional axis substantially parallel to the rotation axis of the engine shaft. When the pendulum masses react to rotational inconsistencies, they oscillate in such a way that the center of gravity of each of said pendulum masses oscillates around an axis substantially parallel to the rotation axis of the engine shaft. The radial position of the center of gravity of each pendulum mass with respect to the rotation axis of the engine shaft, as well as the distance of said center of gravity with respect to the notional oscillation axis, are established so that in response to centrifugal forces, the oscillation frequency of each of the pendulum masses is proportional to the rotation speed of the engine shaft; said multiple can assume, for example, a value close to the preponderant harmonic order of the vibrations responsible for strong rotational inconsistencies.
In devices of the existing art, the pendulum flyweights are generally located radially above the first damping means. In this case the radial dimension of the pendulum flyweights is necessarily limited, so as not to decrease too greatly the installation diameter of the elastic members, and thus decrease the efficiency of the first damping means. Because of these dimensional constraints, in the existing art the mass of the pendulum flyweights can therefore be increased only to the detriment of the efficiency of the damping means having elastic members.
A damping device of this kind is thus more efficient when the mass of the flyweights is increased.